~ Relatives of patients with mood disorders have 1.5-3x greater risk of a mood disorder.

~ Most frequent mood disorder in relatives of those with BPD is MDD.

~ Severity, recurrence and age of onset affects rates in relatives.

Genetic contribution:

~ Severe mood disorders = stronger genetic contribution.

~ Genetic contribution to depression estimated at 40%. Environment plays a large role - it is the unique, non-shared experiences that interact with a biological vulnerability to cause depression.

~ Serotonin is an important gene. Short version = more severe symptoms.

Neurotransmitter systems:

~ Low levels of serotonin implicated in etiology of mood disorders, but only in relation to other neurotransmitters.

~ Primary function of serotonin is to regulate emotions.

~ Currently think it is a balance of various neurotransmitters

~ People with diseases affecting the HPA axis often become depressed. There is increased cortisol levels in depression.

Psychological factors:

~ Learned helplessness: become depressed when make the attribution their actions cannot control their circumstances. Unhelpful attributions: internal, stable, global.

~ Negative cognitive styles are a risk factor for depression.

~ Beck's cognitive model: depression is from a tendency towards automatic negative interpretation of events. Cognitive errors include overgeneralisation, black or white thinking, filtering, personalisation. These errors are about the self, the world and the future (depressive cognitive triad).

~ Response style theory: duration, severity and course are consequences of the way the individual focuses on and appraises their depressive symptoms. Rumination predicts depression onset and duration.

Temple-Wisconsin study:

~ Looking at cognitive vulnerability to depression.

~ Classified as high or low risk and followed prospectively for 5 years.

~ High risk participants were more likely to experience MDE.

What is a major depressive episode?

DSM criteria:

5 or more symptoms present during the same 2 week period:

~ At least one symptom is depressed mood most of the day nearly every day OR anhedonia.

~ Significant weight change or change in appetite.

~ Insomnia or hypersomnia

~ Psychomotor retardation or agitation

~ Loss of energy

~ Worthlessness/guilt

~ Poor concentration, indecisiveness

~ Thoughts of death, suicidal thoughts/plans.

Symptoms represent a change in previous functioning and are persistent (occur for most of the day nearly every day during the same 2 week period).